JPH02234132A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To easily control input signal voltage, to simplify a driving circuit and to accomplish multi-level graduation display with good reproducibility by impressing the voltage in a specific stage on liquid crystal so that the gradation may be controlled. CONSTITUTION:Since a distance between a 1st picture element electrode 6 and a 2nd picture element electrode 7 is different in each one picture element 3, for example, an area where threshold voltage with which the liquid crystal is inverted in one picture element 3 is different is obtained. The voltage of a transition area where the liquid crystal is not inverted completely is not impressed on the liquid crystal but the area of a part where the liquid crystal is inverted completely in one picture element 3 is controlled with the input signal voltage in the specified stage so as to perform the multi-level graduation display. Thus, the input signal voltage is easily controlled and the driving circuit for a liquid crystal display device is simplified. The state of the liquid crystal is stable because it is either the state where the liquid crystal is inverted or the state where the liquid crystal is not inverted in the respective areas in one picture element 3, thereby accomplishing the multi-level graduation display with good reproducibility.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a liquid crystal display device, and particularly to an active matrix type liquid crystal display in which a thin film transistor (TPT) and a pixel electrode are one of the constituent elements of a pixel. It concerns techniques that are effective when applied to equipment. [Prior Art] An active matrix color liquid crystal display device has a liquid crystal display section (liquid crystal display panel) in which a plurality of pixels are arranged in a matrix.

Each pixel of the liquid crystal display section is formed by the intersection of two adjacent scanning signal lines (also referred to as gate signal lines or horizontal signal lines) and two adjacent video signal lines (also referred to as drain signal lines or vertical signal lines). It is placed within the area. The scanning signal lines extend in the column direction (horizontal direction), and a plurality of scanning signal lines are arranged in the row direction (vertical direction). On the other hand, the video signal lines extend in the row direction intersecting the scanning compensation line, and a plurality of video signal lines are arranged in the column direction.

The liquid crystal display section includes a first transparent glass substrate (a lower transparent glass substrate) on which a thin film transistor, a transparent pixel electrode, a protective film for the thin film transistor, and an alignment film for setting the orientation of liquid crystal molecules are sequentially provided. (lower board) and
A second substrate (upper substrate) in which a color filter, a protective film for the color filter, a common transparent pixel electrode, and an alignment film are sequentially provided on a second transparent glass substrate (upper transparent glass substrate), and each orientation of both substrates. It consists of a liquid crystal sealed between membranes and a sealing member for the liquid crystal. In the liquid crystal display section, the first substrate and the second substrate are manufactured separately, and a spacer material is interposed between the two substrates so that the alignment films of both substrates face each other, thereby maintaining a predetermined distance. The first and second substrates are assembled by placing the two substrates on top of each other, sealing the liquid crystal between the two substrates, and sealing them with a sealing member provided along the entire edges of the first and second substrates except for the liquid crystal sealing opening. Note that a backlight is arranged on the first substrate side or the second substrate side. The display screen side is the opposite side of the board from where the backlight is placed. As mentioned above, a pixel mainly consists of a liquid crystal, a transparent pixel electrode and a common transparent pixel electrode arranged with the liquid crystal interposed, a thin film transistor, and a color filter (in the case of a color liquid crystal display device). A transparent pixel electrode, thin film transistor, and color filter are provided for each pixel. Furthermore, one of the source and drain electrodes of the thin film transistor is connected to a transparent pixel electrode, and the other electrode is connected to a video signal line. Further, the gate electrode is connected to a scanning signal line. A color filter is a dyed base material made of a resin material such as Ackonol resin, which is colored with a dye, and is provided for each pixel at a position facing the pixels, and is dyed differently.
That is, the color filter, like the pixel, is configured within the intersection area of two adjacent scanning signal lines and two adjacent video signal lines. In a liquid crystal display device, the brightness of each pixel is usually constant, but in order to improve the image quality, multiple gradations of brightness are sometimes added to each pixel. This method is called a multi-gradation display method.

In the conventional multi-gradation display method, a liquid crystal is enclosed and sealed between a transparent pixel electrode and a common transparent pixel electrode (more specifically, a liquid crystal is sealed between a transparent pixel electrode and a common transparent pixel electrode and the liquid crystal). The voltage in the transient region where the alignment film, etc. is present) is not sufficiently inverted between the pixel electrodes of a given pixel (i.e.,
(between a transparent pixel electrode and a common transparent pixel electrode), and by controlling the inversion angle of the liquid crystal, that is, the light transmittance, for each pixel, multiple gradations are achieved.

It goes without saying that by providing a color filter between one of the transparent glass substrates and the transparent pixel electrode, multi-gradation display, that is, multi-color display, is possible using the same method. Active matrix liquid crystal display devices using TPT are described, for example, in "R Nikkei Electronics," p. 211 (September 10, 1984, published by Nikkei McGraw-Hinore).
It is publicly known. [Problems to be Solved by the Invention] In conventional liquid crystal display devices, in order to perform multi-gradation display, as mentioned above, a voltage in a transient region where the liquid crystal is not sufficiently inverted is applied to the liquid crystal, and the inversion angle of the liquid crystal, that is, the light Multiple gradations are achieved by controlling the transmittance of the light. However, since the amount of change in voltage is small compared to the amount of change in the inversion angle of the liquid crystal, it is difficult to control the voltage in the conventional method, which poses the problem of complicating the driving circuit of the liquid crystal display device. Furthermore, since the liquid crystal to which the above-mentioned transient voltage is applied is in an unstable state in which it does not completely reverse, there is a problem of poor reproducibility.

The purpose of the present invention is not to provide a multi-gradation display using an unstable state in which the liquid crystal does not completely invert, as in the past.
The purpose of this method is to make it easy to control the voltage, simplify the drive circuit, and realize multi-gradation display with good reproducibility. [Means for Solving the Problems] In order to achieve the above object, the liquid crystal display device of the present invention includes a first pixel electrode provided on a first transparent glass substrate, and a second transparent glass substrate. The feature is that the distance between each pixel and the second pixel electrode provided above is different for each pixel. Is the distance between the first picture copper electrode and the second picture element electrode different? For example, one of the first electrode and the second electrode is configured to have a stepped or sloped shape so that the thickness thereof gradually changes.

[Effect]

The distance between the first pixel electrode and the second pixel electrode is related to the voltage at which the liquid crystal is inverted, that is, the threshold voltage. The larger the distance between the electrodes, the higher the threshold voltage, and the smaller the distance between the electrodes, the lower the threshold voltage. In other words, if regions with different distances between electrodes are created within each pixel, the area of the region where the liquid crystal is inverted within one pixel will change depending on the magnitude of the input signal voltage and voltage (image signal), and as a result, Since the aperture ratio of one pixel, that is, the light transmittance changes for each pixel, it appears to the human (user) eye as multiple gradations depending on the image signal.

As described above, in the liquid crystal display device of the present invention, since the distance between the first pixel electrode and the second pixel electrode is different in each pixel, the threshold voltage for inversion of the liquid crystal differs within each pixel. Therefore, for example, at a certain voltage V, the liquid crystal inverts by 1/3 (i.e., opens or transmits light) within one pixel, and at another voltage, v2, which is greater than vE.
In this case, the portion of the liquid crystal that is inverted within one pixel changes depending on the voltage applied between the electrodes, such that the liquid crystal is inverted by 1/2 within one pixel. Moreover, in each region within one pixel, the liquid crystal is either completely inverted or not completely inverted, and the state of the liquid crystal is stable. That is, in the present invention, instead of applying a voltage to the liquid crystal in a transient region where the liquid crystal is not sufficiently inverted as in the conventional case,
, the area of a completely inverted portion within one pixel is controlled by input signal voltages at predetermined levels, and multi-gradation display is performed. Therefore, the input signal voltage can be easily controlled, and the parking circuit of the liquid crystal display device can be simplified. In addition, in each region within a pixel, the liquid crystal is either inverted or not inverted, and the state of the liquid crystal is stable, making it possible to realize multi-gradation display with good reproducibility. ．． It goes without saying that by providing a color filter between one of the transparent glass substrates and the pixel electrode, multi-gradation display, that is, multi-color display, is possible using the same method.

〔Example〕

FIGS. 1A to 1D are diagrams for explaining embodiments of the liquid crystal display device of the present invention, respectively.

Figure 1 (A) is a schematic plan view of one pixel, Figure 1 (B) -
(D) is a schematic sectional view taken along section line 81A' in FIG. 1(A), showing the first to third embodiments.

In the figure, 1 is a video signal line (drain signal line or vertical signal line), 2 is a scanning signal line (gate signal line or horizontal signal line), 3 is one pixel, 4 is a gate electrode, and 5 is a transparent glass substrate (first signal line). 1 transparent glass substrate or lower transparent glass substrate), 6 is a first transparent pixel electrode, 7 is a second transparent pixel electrode (common transparent pixel electrode), and 8 is a liquid crystal. In addition, the second
The transparent glass substrate (upper transparent glass substrate), source and drain electrodes of the thin film transistor, alignment film, etc. are not shown. The first pixel electrodes 6 are divided and provided for each pixel, so the number of first pixel electrodes 6 is equal to the number of pixels, and is connected to the source electrode of a thin film one helangistor which is a switching element of the pixel. The second pixel electrode 7 is provided commonly to all pixels. The liquid crystal display section will be explained in detail later using drawings. In the first embodiment shown in FIG. 1(B), the second pixel electrode 7 is formed in a stepwise manner so that the thickness of the second pixel electrode 7 changes in five steps from A to E. There is. That is, the distance between the second pixel electrode 7 and the eleventh pixel electrode 6 changes in five steps. It goes without saying that each pixel has the same configuration.

The threshold voltage of the liquid crystal is lower as the distance between the electrodes is smaller, so the threshold voltage Vth of the liquid crystal in each area of ABCDE is as follows:
Vth^ (threshold voltage of region A, the same applies hereafter) <Vt
In the pixels where six input signal voltages Vl (Vth^<Vz<VthB) with hs<Vthc<Vthp<VthE are applied between the first and second pixel electrodes, only the liquid crystal in the area A is Invert. In addition, the input signal voltage Vz (V tha < V2 < V L++c)
In the pixel to which is applied, only the liquid crystals in the A region and the B region are inverted. That is, depending on the magnitude of the input signal voltage, the area in which the liquid crystal is inverted within each pixel, that is, the aperture ratio (light transmittance) changes, which appears to the human eye as multiple gradations. Moreover, in each region within one pixel,
The liquid crystal is either completely inverted or not completely inverted, and the state of the liquid crystal is stable.

Therefore, in the liquid crystal display device of this embodiment, the voltage can be easily controlled, the drive circuit can be simplified, and a multi-gradation display with good reproducibility can be realized.

In the first embodiment shown in FIG. 1(B), the second pixel electrode 7 is formed in multiple stages, but in the second embodiment shown in FIG. 1@(C), the first pixel electrode 6 The thickness of A-E is 5
The first pixel electrode is formed in a stepwise manner so as to change in stages. That is, the distance between the first pixel electrode 6 and the second pixel electrode 7 changes in five steps. The operation and effect of this embodiment are exactly the same as those of the first embodiment. In the third embodiment shown in FIG. 1(C), the second pixel electrode 7 is formed not in a stepped shape but in a sloped shape. The operation and effect of this embodiment are also similar to those of the first embodiment. In this example, the shape of the electrode is not stepped, but
Since it has a sloped shape, analog gradation display is also possible. A known method can be used to form a stepped pixel electrode or a sloped pixel electrode, as shown in FIG. 1(B).
To form the stepped pixel electrode shown in , (C), for example, first, after depositing the electrode material to the thickness of the E region,
Electrode material is deposited again, covering only the area with a mask. Next, this can be achieved by repeating the process of covering only the D region with a mask and depositing the electrode material again. 1st
The sloped pixel electrode shown in Figure (D) can be formed, for example, by gradually moving the mask in the direction of the arrow while depositing the electrode material.

Next, a liquid crystal display device to which the present invention is applied will be explained in detail. Fig. 2 is a plan view of a main part of one pixel of the liquid crystal display section of an active matrix color liquid crystal display device to which the present invention is applied, and Fig. 3 is a plan view taken along the cutting line 1-1 of Fig. 2. FIG. 4 is a sectional view of the portion and the vicinity of the seal portion, and FIG. 4 is a plan view of the main part of the liquid crystal display section in which a plurality of pixels shown in FIG. 2 are arranged.

As shown in FIG. 3, a thin film transistor TPT and a transparent pixel electrode ITO are provided on the inner surface (liquid crystal side) of the lower transparent glass substrate SUB1. The lower transparent glass substrate SUBI has a thickness of about 1.10111 mm, for example. In this embodiment as well, although not shown in detail in FIG. 3, the distance between the transparent pixel electrode IT○ on the transparent glass substrate SUBI side and the common transparent pixel electrode ITO on the transparent glass substrate SUBZ side varies. One side of the transparent pixel electrode ITO is formed into a stepped or sloped shape, which is different for each pixel. As shown in Figure 4, each pixel is connected to two adjacent scanning signal lines (gate signal line or horizontal signal line) OL and two adjacent video signal lines (drain signal line or vertical signal line) DL. It is located within the intersection area (within the area surrounded by four signal lines). Scanning signal line G
As shown in FIGS. 2 and 4, the L extends in the column direction (horizontal direction) and is arranged in plural in the row direction (vertical direction). The video signal lines DL extend in the row direction, and a plurality of video signal lines DL are arranged in the column direction. The thin film transistor TPT of each pixel has three
The thin film transistor (divided thin film transistor) TFTI. It is composed of TFT2 and TFT3. Thin film transistors TFTI to TFT3. Each of them is constructed with substantially the same dimensions (same channel length and channel width). Each of the divided thin film transistors TPTI to TFT3 mainly includes a gate electrode GT, an insulating film GI. Type I (intrins)
ic, an i-type semiconductor layer As made of silicon (Si) not doped with conductivity type determining impurities, and a pair of source electrode SDI and drain electrode SD2.

Note that the source and drain are originally determined by the bias polarity between them, and in the circuit of this liquid crystal display device, the polarity is reversed during operation, so it should be understood that the source and drain are interchanged during operation. However, in the following description as well, for convenience, one SDI is fixed as a source and the other SD2 is fixed as a drain.

The gate 1 electrode GT is connected to the scanning signal line G as shown in detail in FIG.
It is configured in a T-shape (branched into a T-shape) protruding from L in the row direction (downward in FIGS. 2 and 5). That is, the gate electrode GT is configured to extend substantially parallel to the video signal line DL.

The gate electrode GT is a thin film transistor T FT 1 to T
It is configured to protrude to each formation region of FT3. Thin film transistor TPT1~TFT3
The respective gate electrodes GT are integrally formed (as a common gate electrode) and are continuously provided on the same scanning signal line GL. The gate electrode GT is formed of a single-layer J-th conductive film g1 so as to avoid forming a large step as much as possible in the formation region of the thin film transistor Tl''T. (Cr) film with a film thickness of about 1100. This gate electrode GT is shown in FIGS. It is thicker than the i-type semiconductor layer AS so as to completely cover the i-type semiconductor layer AS (as seen from below). Therefore, when a backlight such as a fluorescent light is attached below the lower transparent glass substrate SUBI, This opaque Cr gate electrode 1, iGT forms a shadow, and the semiconductor NA.S is not exposed to backlight light, making it difficult for the conduction phenomenon caused by light irradiation, that is, the deterioration of the off-characteristics of the TFT, to occur. ,
The original size of the gate 1 electrode GT is the minimum width necessary to span the source/drain electrodes SDI and SDZ (including the alignment margin between the gate electrode and the source/drain electrodes), and the channel dNAW The depth length that determines the distance between the source and drain electrodes (channel length) L
It is determined by the factor W/L that determines the ratio of mutual conductance gm, that is, the mutual conductance gm. The size of the gate electrode in this liquid crystal display device is of course larger than the original size mentioned above.

Gate electrode GT and its wiring GL may be provided integrally in a single layer, considering only the function of the gate and light shielding of the gate electrode GT. In this case, Si is contained as an opaque conductive material. Aluminum (AI2), pure AQ
, and A. containing palladium (Pd). You can choose Q etc.

Here, the scanning signal line GL is composed of a composite film consisting of a first conductive film g1 and a second conductive film g2 provided on top of the first conductive film g1. The first conductive film g1 of the scanning signal line GL is provided in the same manufacturing process as the first conductive film g1 of the gate electrode GT, and is configured integrally with the first conductive film g1 of the gate electrode GT. The second conductive film g2 is, for example, an AQ film provided by a sputtering method, and
It will be installed with a thickness of about 4,000 people. The second conductive film g2 can reduce the resistance value of the scanning signal line GL and increase the signal transmission speed (pixel information writing characteristics).
The scanning signal line O L has a second width compared to the width of the first conductive film g1.
The width of the conductive film g2 is configured to be small. That is, the scanning signal line GL is configured so that the step shape of its side wall can be made gentle, so that the surface of the insulating film GI provided thereabove can be flattened.

The insulating film GI is the thin film transistor T P T 1 to TF
T3 is used as the respective gate f4 membrane. The insulating film GI is connected to the gate electrode GT and the scanning signal line G.
It is provided on the first layer of L. For example, a silicon nitride film provided by plasma CVD method is used as the insulating film GI.
Provided with a film thickness of about 00 people. As mentioned above, the insulating film Gl
The surface of the thin film transistor TFT 1. The regions where the TFTs 3 and the scanning signal lines GL are formed are flattened.

The i-type semiconductor layer AS is used as a channel forming region for each of the thin film transistors TFTI to TFT3 divided into a plurality of parts, as shown in detail in FIG. 6 (plan view of main part in a predetermined manufacturing process). The i-type semiconductor layers As of the TFTs 3 are integrally formed within the pixel. That is, each of the plurality of divided thin film transistors TPT1 to TFT3 of a pixel is constituted by an island region of one (common) i-type semiconductor layer As. The i-type semiconductor layer AS is formed of a non-quality silicon film or a polycrystalline silicon film, and has a thickness of about 2000 nm.

This i-type semiconductor layer AS is made of Si by changing the components of the supplied gas.
, N4, the lower transparent glass substrate SUBI was formed using the same plasma CVD apparatus.
is provided without being taken out of the device. Further, a P-doped N+ type semiconductor layer do (FIG. 3) for ohmic contact is similarly continuously provided to a thickness of about 300 layers. After that, the lower transparent glass substrate SUBI
is taken out from the CVD apparatus, and the N+ type semiconductor layer dO and the i type semiconductor layer AS are formed by photolithography (photographic processing) as shown in FIGS. 2 and 3.

In this way, by integrally configuring the respective i-type semiconductor layers AS of the thin film transistors TPTI to TFT3 divided into a plurality of parts in one pixel, the thin film transistor T
Drain electrode SD common to each of PTI to TFT3
2 is the i-type semiconductor layer AS (actually, the thickness of the first conductive film g1, the thickness of the N4'' type semiconductor layer do, and the i-type semiconductor layer A
Since the step (corresponding to the film thickness obtained by adding the film thickness of S) is only crossed once from the drain electrode SD2 side toward the i-type semiconductor IAs side, the probability that the drain electrode SD2 will be disconnected is low, and point defects will occur. It is possible to reduce the probability of That is, in this liquid crystal display device, the point defects that occur within the pixel when the drain electrode SD2 crosses the step of the i-type semiconductor layer AS can be reduced to one-third.

Although it is different from the layout of this liquid crystal display device, the video signal line DL directly crosses over the i-type semiconductor layer AS, and the video signal fiDL in this overpassed portion is transferred to the drain electrode SD2.
When configured as a video signal line DL (drain electrode S
It is possible to reduce the probability of line defects occurring due to disconnection when D2) crosses over the i-type semiconductor layer AS. That is, by integrally configuring the respective i-type semiconductor layers As of the thin film transistors TPTI to TFT3 divided into a plurality of parts within one pixel, the video signal line DL (drain electrode SD2) can connect the i-type semiconductor layer As only once. (Actually, there are two stages at the beginning and end of the ride.)
degree). The i-type semiconductor layer AS is shown in FIGS. 2, 6, and 7 (plan views of main parts of pixels in predetermined manufacturing steps).
As shown in detail in , the scanning signal line GL and the video signal line DL
It is provided to extend between the two parts at the intersection (crossover part). This extended i-type semiconductor layer AS is
It is configured to reduce short circuits between the scanning signal line GL and the video signal line DL at the intersection. Thin film transistor TPT1 divided into multiple parts within one pixel
~As shown in detail in FIGS. 2, 3, and 7, the respective source electrodes SDI of the TFTs 3 and the common drain electrode SD2 are provided separately on the i-type semiconductor layer As. .

Each of the source electrode SDI and drain electrode SD2 is
The structure is such that when the bias polarity of the circuit changes, the source and drain switch places in operation. That is, the thin film transistor TPT is bidirectional like a FET (field effect transistor).

Each of the source electrode SDI and drain electrode SD2 is
From the lower layer side in contact with the N+ type semiconductor layer do, a first conductive film d1, a second conductive film d2 . It is constructed by sequentially overlapping third conductive films d3. First conductive film d of source electrode SDI
1, the second conductive film d2 and the third conductive film d3 are provided in the same manufacturing process as each of the drain electrodes SD2.

The first conductive film d1 is a Cr film provided by sputtering,
Film thickness of 500 to 1000 people (in this liquid crystal display device, 6
00 people). If the Cr film is made thicker, the stress will increase, so the Cr film is provided within a range that does not exceed the thickness of about 2,000 people. The Cr film is an N+ type semiconductor/
Good contact with ldo. The Cr film is used in the second
It forms a so-called barrier layer that prevents AI2 of the conductive film d2 from diffusing into the N+ type semiconductor layer do. First conductive film d
In addition to the Cr film, high melting point metals (Mo, Ti.
(Ta, W) film, high melting point metal silicide (MoSi2, T
iSi,, T a S i2, WSi,) film may be used.

After patterning the first conductive film d1 using photolithography technology, the same photomask is used to pattern the first conductive film d1 or the first conductive film d1.
The N+ type semiconductor layer dO is removed using the conductive film d1 as a mask. In other words, the N+ remaining on the i-type semiconductor layer AS
The portion of the type semiconductor layer dO other than the first conductive film d1 is removed by self-alignment (self-alignment). At this time, the N1 type semiconductor layer dO is etched so that its entire thickness is removed, so the i type semiconductor layer AS is also slightly etched at its surface, but the extent can be controlled by the etching time. ．． Thereafter, the second conductive film d2 is formed to a thickness of 3,000 to 5,500 layers (in this liquid crystal display device, the thickness is about 3,500 layers) by supersorting AQ. AQ film is C
It has less stress than the r film, can be formed thicker, and is configured to reduce the resistance values of the source electrode SDI, drain electrode SD2, and video signal line DL. That is, the second conductive film d2 is configured to increase the operating speed of the thin film transistor TPT and the signal transmission speed of the video signal line DL. Therefore, the writing characteristics of the pixel can be improved by the second conductive film d2. As the second conductive film d2. In addition to the AQ film, the AQ film contains Si, copper (Cu), and Pd as additives. It may also be provided with a membrane.

After the second conductive film d2 is patterned by photolithography, a transparent conductive film (I The third conductive film d3 is provided by 'r○: Nesa film).

This third conductive film d3 constitutes the source electrode SDI, drain electrode SD2, and video signal line DL, and also constitutes the transparent pixel electrode IIT○.

The first conductive film d1 of the source electrode SDI and the drain electrode SD2 is fixed to the second conductive film d1 even if mask misalignment occurs in the manufacturing process between the first conductive film d1 and the second conductive film d2 and third conductive film d3. The side where the channel is provided is configured to have a larger dimension than the conductive film d2 and the third conductive film d3 (channel formation of each of the first conductive film d1 to the third conductive film d3). (The area side may be on-the-line). Further, each of the first conductive films d1 of the source electrode SD1 and the drain electrode SD2 is configured to define the gate length L of the thin film transistor TPT.

In this way, in the thin film transistors T P T l to TFT3 divided into a plurality of parts within one pixel, the source electrode S
First conductive film d1 of each of DI and drain electrode SD2
By configuring the channel forming region side of the thin film transistor to have a larger dimension than the second conductive film d2 and the third conductive film d3, the dimension between the first conductive film d1 and the source electrode SDI and the drain electrode SD2 can be The separation dimension (gate length) between the first conductive films dl, which can define the gate length L of TPT, can be defined by processing accuracy (patterning accuracy), so the thin film transistor TP
The gate length I4 of each of T1 to TFT3 can be made uniform.

The source electrode SDI is . As mentioned above, the transparent pixel electrode IT
Connected to O. The source electrode SDL has a step shape of the i-type semiconductor layer AS (a step corresponding to the sum of the thickness of the first conductive film g1, the thickness of the N1-type semiconductor layer dO, and the thickness of the i-type semiconductor layer AS). ). Specifically, the source voltage WAS D t is an i-type semiconductor l.
A. The first conductive film d provided along the step shape of S
1. A second conductive film d2 is provided above the first conductive film d1 with a smaller dimension on the side connected to the transparent pixel electrode To, and a second conductive film exposed from the second conductive film. and a third conductive film d3 connected to d1. The first conductive film d1 of the source electrode SDI has good adhesion to the N+ type semiconductor layer do, and is mainly configured as a barrier layer against diffused substances from the second conductive film d2. The second conductive film d2 of the source electrode SDI cannot be formed thickly because the Cr film of the first conductive film d1 increases stress, and cannot overcome the step shape of the i-type semiconductor layer AS. It is configured to overcome the layer AS. That is, the second conductive film d2 can be provided thickly to improve the step force barrier (step coverage 1).The second conductive film d2 can be provided thickly to improve the resistance value of the source electrode SDI (drain electrode SD2). and the same applies to the video signal line DL).The third conductive film d3 greatly contributes to the reduction of the
Since the step shape caused by S cannot be overcome, the second conductive film d2 is configured to have a smaller dimension so as to be connected to the exposed first conductive film d1. 1st
The conductive film d1 and the third conductive film d3 not only have good adhesiveness but also have a small step shape at the connecting portion between them, so that they can be reliably connected.

In this way, the source electrode SD of the thin film transistor TPT
I, a first conductive film d1 as a pariah layer provided along at least the i-type semiconductor layer AS, and this first conductive film d
A second conductive film d2 is provided on top of the first conductive film d1 and has a smaller specific resistance value than the first conductive film d1, and a second conductive film d2 having smaller dimensions than the first conductive film d1. By connecting the third conductive film d3, which is a transparent pixel electrode ITO, to the exposed first conductive film d1, the thin film transistor TP
Since the T and the transparent pixel electrode ITO can be reliably connected, point defects caused by disconnection can be reduced. Moreover, since the first conductive film d1 has a barrier effect, the source electrode SDI has a second conductive film d2 (with a low resistance value).
AQ film) can be used, so the resistance value can be reduced.

The drain electrode SD2 is configured integrally with the video signal line DL, and is provided in the same manufacturing process. The drain electrode SD2 has an L-shape that protrudes in the column direction intersecting the video signal line DL. That is, each drain electrode SD2 of the thin film transistors TPTI to TFT3 divided into a plurality of parts within one pixel is connected to the same video signal line D.
A transparent pixel electrode ITO connected to L is provided for each pixel,
It constitutes one of the pixel electrodes of the liquid crystal display section.

The transparent pixel electrode ITO includes three transparent pixel electrodes (divided transparent pixel electrodes) ITOI, corresponding to each of the thin film transistors TPTI to TFT3 divided into a plurality of parts within one pixel,
It is divided into ITO2 and ITO3. The transparent pixel electrode ITOI is connected to the source electrode SD1 of the thin film transistor TFTI. The transparent pixel electrode ITO2 is connected to the source electrode SD1 of the thin film transistor TFT2. The transparent pixel electrode ITO3 is a thin film transistor T
It is connected to the source electrode SDI of FT3.

Each of the transparent pixel electrodes IT○1 to ITO3 has substantially the same dimensions as each of the thin film transistors TPT1 to TFT3.

Each of the transparent pixel electrodes ITOI to ITO3 has the respective i-type semiconductor layers AS of the thin film transistors TPTI to TFT3 integrally configured (the divided thin film transistors TPT are arranged in a concentrated manner). It is constructed in an L-shape. In this way, the thin film transistor TPT is divided into a plurality of thin film transistors TPT1 to TFT3 within one pixel arranged in the intersection area of the two adjacent scanning signal lines GL and the two adjacent video signal lines DL. By connecting each of the plurality of divided transparent pixel electrodes ITOI to ITO3 to each of the plurality of divided thin film transistors TPTI to TFT3, only a part of the divided pixel (for example, the thin film transistor TFTL) becomes a point defect. Since the pixel as a whole is no longer a point defect (the thin film transistors TFT2 and TFT3 are not point defects), it is possible to reduce point defects in the pixel as a whole. In addition, some of the point defects in which the pixel is divided are smaller than the entire area of the pixel (in the case of this liquid crystal display device, the area is one-third of the pixel), so the point defects can be made difficult to see. I can do it.

In addition, the divided transparent pixel electrodes IT01 to I of the above pixels
By configuring each TO3 to have substantially the same size, the area of a point defect within a pixel can be made uniform.

Furthermore, the divided transparent pixel electrode work TOI of the above pixel ~
By configuring each of the IT○3 to have substantially the same dimensions, the common transparent pixel electrode IT○ of each of the transparent pixel electrodes ITOI to ITO3 and the upper transparent glass substrate SUB2
and the transparent pixel electrodes ITOI to ITO3 added to each of the transparent pixel electrodes ITO1 to ITO3 and the gate electrode GT.
The overlapping capacitance (Cgs) generated by overlapping with the above can be uniformly resized. That is, the transparent pixel electrode I
Since each of TOI to ITO3 can make the liquid crystal capacitance and superposition capacitance uniform, it is possible to make the DC component applied to the liquid crystal molecules of the liquid crystal LC due to this superposition capacitance uniform, and this When a method of canceling the DC component is adopted, it is possible to reduce the variation in the DC component applied to the liquid crystal of each pixel. A protective film PSVI is provided over the thin film transistor TPT and the transparent pixel electrode TTo.

The protective film psvi is numbered mainly to protect the thin film transistor TPT from moisture, etc., and a film with high transparency and good moisture resistance is used.

The protective film PSVI is formed of, for example, a silicon oxide film or a silicon nitride film provided by a plasma CVD method, and
~11,000 film thickness (8,000 film thickness for this liquid crystal display device)
The thickness of the film is approximately that of a human body.

A shielding film LS is provided above the protective film PSVI on the thin film transistor TFT to prevent external light from entering the i-type semiconductor layer AS used as a channel formation region. As shown in Fig. 2, the shielding film LS is configured within the area surrounded by the dotted line.The shielding film LS is made of a film having high light shielding properties, such as an AQ film or a Cr film. The thickness of the film is approximately 1,000 mm using the sputtering method.
Therefore, the common semiconductor layer A. of the thin film transistors TPTI to TFT3. S is sandwiched between the upper and lower light shielding films LS and the gate electrode GT, so that the i-type semiconductor layer AS is not exposed to external natural light or backlight light. Light shielding film LS and gate electrode GT are semiconductor/F
It is thicker in size than FAS and is provided in a similar shape, and the size of both is said to be almost the same (in the figure, the gate electrode GT is drawn smaller than the light shielding film LS so that the boundary line can be seen). .

Note that the backlight can be attached to the upper transparent glass substrate SUB2 side, and the lower transparent glass substrate SUBI can be placed on the a-side (externally exposed side). In this case, the light-shielding film LS is connected to the backlight light, and the gate electrode GT is connected to the backlight. It acts as a light shield for natural light. The thin film transistor TPT is configured such that when a positive bias is applied to the gate electrode GT, the channel resistance between the source and drain becomes small, and when the bias is set to O, the channel resistance becomes large. In other words, wtr!
The A transistor TPT is configured to control the voltage applied to the transparent pixel electrode IT○ by the bias applied to the gate electrode [iGT.

The liquid crystal LC is sealed between a lower alignment film ORII and an upper alignment film ORI2 that set the orientation of liquid crystal molecules in a space provided between a lower transparent glass substrate SUBI and an upper transparent glass substrate SUB2. .

The lower alignment film ORII is provided above the protective film PSVI on the lower transparent glass substrate SUBI side.

On the inner surface (liquid crystal side) of the upper transparent glass substrate SUB2, a color filter FIL, a protective film P Sv2, a common transparent pixel electrode (COM) ITO, and an upper alignment film ○RI2 are disposed.
are sequentially stacked.

The common transparent pixel electrode ITO is connected to the lower transparent glass substrate SUB.
It faces the transparent pixel electrode ITO provided for each pixel on the I side, and is configured integrally with another adjacent common transparent pixel electrode ITO. The configuration is such that a common voltage Vco is applied to this common transparent pixel electrode ITO. The common voltage Vcom is a low-level driving voltage Vdwin applied to the video signal line DL and a high-level driving voltage V
This is the intermediate potential between dmax and dmax. The color filter FIL is configured by coloring a dyed base material made of a resin material such as acrylic resin with a dye.

The color filter FIL is arranged for each pixel at a position facing the pixel, and is colored differently. That is, the color filter FIL, like the pixel, is configured within the intersection area of two adjacent scanning signal lines GL and two adjacent video signal lines DL. Each pixel has a color filter F
Each predetermined color filter of the IL is divided into a plurality of parts.

The color filter FIL can be provided as follows. First, a dyed base material is provided on the surface of the upper transparent glass substrate SUB2, and the dyed base material other than the red filter forming area is removed using photolithography technology. Thereafter, the dyed base material is dyed with a red dye, subjected to a fixation treatment, and a red filter R is provided. Next, a green filter G and a blue filter B are sequentially provided by performing similar steps.

In this way, by providing each color filter of the color filter FIL in the intersection area facing each pixel, the scanning signal line GL,
Since each of the video signal lines DL exists, it is possible to secure a positioning margin between each pixel and each color filter of the color filter FIL (increase the positioning margin) by an amount corresponding to the existence of the video signal lines DL. Furthermore, when providing each color filter of the color filter FIL, it is possible to secure alignment margin between different color filters. That is, in this liquid crystal display device, a pixel is formed within the intersection area of two adjacent scanning signal lines OL and two adjacent video borrow lines DL, and this pixel is divided into a plurality of parts, and a pixel opposite to this pixel is formed. By providing each color filter of the color filter FIL in the position where the color filter FIL is located, it is possible to reduce the above-mentioned point defects and to secure alignment allowance between each pixel and each color filter. This is provided to prevent the dyes that dye the filter FIL into different colors from leaking into the liquid crystal LC. The protective film PSv2 is made of a transparent resin material such as acrylic resin or epoxy resin. In this liquid crystal display device, each layer on the lower transparent glass substrate SUBl side and each layer on the upper transparent glass substrate SUBZ side are provided separately, and then the lower transparent glass substrate SUBI and the upper transparent glass substrate SUB2 are stacked. They are assembled by aligning them together and sealing a liquid crystal LC between them. As shown in FIG. 4, a plurality of pixels of the liquid crystal display section are arranged in the same column direction as the direction in which the scanning signal line OL extends, and are arranged in pixel columns x1, X,, x3, x4, . . . It consists of Each pixel column X1, X2, X3
,
○The arrangement position of 3 is configured to be the same in each column.
That is, in each pixel of the pixel columns XE, X3, . . . , the thin film transistors TPTI to TFT3 are arranged on the left side, and the transparent pixel electrodes ITOI to ITO3 are arranged on the right side. Each pixel in the next pixel column x2, X4,... in the row direction of each pixel column X1, X,... It is composed of pixels arranged line-symmetrically with respect to gDL.

That is, pixel columns X2, X. , . . . , the thin film transistors TPT1 to TFT3 are arranged on the right side, and the transparent pixel electrodes ITO1 to ITO3 are arranged on the left side. Then, pixel rows X,, X4,...
Each pixel of .
staggered).

That is, if each pixel interval of the pixel column X is 1.0 (1.0 pitch), then the pixel interval of the next stage pixel column X is 1.
0, and is shifted by 0.5 pixel interval (0.5 pitch) in the column direction with respect to the previous pixel column X. The video signal line DL extending in the row direction between each pixel is configured to extend in the column direction by a half pixel interval (0.5 pitch) between each pixel column X.

In this way, in the liquid crystal display section, the thin film transistor TP
A plurality of pixels having the same T and transparent pixel electrode ITO are arranged in the column direction to form a pixel column
The next pixel row X is composed of pixels arranged in line symmetry with the pixels of the previous pixel row By moving and configuring, as shown in FIG. 8 (a plan view of the main part in a state where pixels and color filters are overlapped),
The pixel (
For example, a pixel provided with a red filter R in pixel row X3) and a pixel provided with the same color filter in the next pixel row , can be separated by 5 pixel intervals (1.5 pitch). That is, the pixels of the previous pixel column
The color filter FIL constitutes a triangular arrangement structure of ROB. The RGB triangular arrangement structure of the color filter FIL can improve the mixing of each color, and therefore can improve the resolution of a color image.

Moreover, since the video signal line DL extends in the column direction by only half a pixel interval between each pixel column X, it does not intersect with the adjacent video signal line DL. Therefore, it is possible to eliminate the routing of the video signal line DL and reduce the area occupied by the video signal line DL, and it is also possible to eliminate the detour of the video signal line DL and eliminate the multilayer wiring structure.

The circuit configuration of this liquid crystal display section is shown in FIG. 9 (equivalent circuit diagram of the liquid crystal display section).

XiG, Xi+IG, . . . shown in FIG. 9 are video signal lines DL connected to pixels in which the green filter G is provided. XiB, Xi+IB,... is blue filter B
This is a video signal MDL connected to a pixel in which a pixel is provided.

Xi+IR, Xi+2R. ... is a video signal line DL connected to a pixel in which a red filter R is provided. These video signal lines DL are selected by a video signal drive circuit. Yi is a scanning signal iiGL that selects the pixel column X1 shown in FIGS. 4 and 8. Similarly, Y i +
1, Y i + 2, - are scanning signal lines GL that select pixel columns x2, X, . . . , respectively. These scanning signal lines OL are connected to a vertical scanning circuit.

The center part of FIG. 3 shows a cross section of one pixel, while the left side shows a cross section of the left edge part of the lower transparent glass substrate SUBI and the upper transparent glass substrate SUB2 where external lead wiring is present. On the right is a transparent glass substrate SUB
A cross section of the right edge portion of I and SUB2 where no external lead wiring is present is shown.

The sealing materials SL shown on the left and right sides of Fig. 3 are as follows:
It is configured to seal the liquid crystal LC, and is provided along the entire edges of the transparent glass substrates SUBI and SUB2 except for the liquid crystal sealing opening (not shown). The sealing material SL is made of, for example, epoxy resin.

Upper transparent glass substrate SUBlt! The common transparent pixel electrode TO of I is made of silver paste 14J at least in one place.
It is connected to the external lead wiring provided on the lower transparent glass substrate SUBI side by SIL. This external lead wiring is connected to the gate electrode GT and source electrode SDI described above.
, and are provided in the same manufacturing process as each of the dome electrodes SD2.

Orientation films ORII and ○RI2, transparent pixel electrode ITO,
Common transparent pixel electrode ITO, protective film psv1 and PSV
2. Each layer of the insulating film GI is provided inside the sealing material SL. The polarizing plate POL has a lower transparent glass substrate S
UBI is provided on the outer surface of each of the upper transparent glass substrate STJB2. FIG. 10 is a sectional view of a main part of a pixel and a periphery of a sealing part of a liquid crystal display section of another active matrix type color liquid crystal display device to which the present invention is applied, and FIG.
A plan view showing one pixel of the liquid crystal display section of the liquid crystal display device shown in the figure, FIG. 12 is a cross-sectional view of the portion taken along the line A-A in FIG. 11, and FIG. 13 is a pixel shown in FIG. 11. 14 to 16 are plan views of main parts of a liquid crystal display section in which a plurality of are arranged.
A plan view of main parts in a predetermined manufacturing process of the pixel shown in FIG.
FIG. 17 is a plan view of the main parts in a state where the pixels and color filters shown in FIG. 13 are superimposed. In this liquid crystal display device, it is possible to improve the aperture ratio of each pixel in the liquid crystal display section, reduce the direct current component applied to the liquid crystal, reduce point defects in the liquid crystal display section, and reduce black unevenness. Can be done. In this embodiment as well, although not shown in detail in FIG. 10, the transparent pixel electrode ITOI on the transparent glass substrate SUBI side
and a common transparent pixel electrode IT on the transparent glass substrate SUBZ side.
One of the transparent pixel electrodes is formed in a stepped or sloped shape so that the distance from O2 (COM) is different for each pixel.

In this liquid crystal display device, as shown in FIG.
It is divided into FTI to TFT3. In other words, the thin film transistor T divided into a plurality of parts within one pixel
Each of PT1 to TFT3 is composed of an independent island region of an i-type semiconductor layer As.

Further, each of the transparent pixel electrodes ITOI to ITO3 connected to each of the thin film transistors TPTI to TFT3 is overlapped with the scanning signal RiAGL of the next stage in the row direction on the side opposite to the side connected to the thin film transistors TPT1 to TFT3. It has been done. This superposition is
A holding capacitor element (electrostatic capacitor element) Cadd is configured in which each of the transparent pixel electrodes ITOI to IT○3 is used as one electrode and the scanning signal line GL of the next stage is used as the other electrode. The dielectric film of this storage capacitor element C add is made of the same layer as the insulating film GI used as the gate insulating film of the thin film transistor TPT.

The gate electrode GT is provided to be thicker than the i-type semiconductor layer AS, similar to the liquid crystal display device shown in FIG. ~
Since the TFT3 is provided for each independent i-type semiconductor layer AS, a thick pattern is provided for each thin film transistor TPT.

In addition, the scanning signal line GL of the upper transparent glass substrate StJB2
．． Since the black matrix pattern BM is provided in the part corresponding to the video signal @DL and the thin film transistor TPT, the outline of the pixel becomes clear, improving the contrast and preventing external natural light from hitting the thin film transistor TPT. Can be done. FIG. 18 shows an equivalent circuit of the pixel shown in FIG. 11.

In FIG. 18, as described above, Cgs is the gate electrode GT and source electrode SDI of the thin film transistor TPT.
is the superposition capacitance formed by . Overlap capacity C
The dielectric film of gs is an insulating film GI. Cpix is the liquid crystal capacitance formed between the transparent pixel electrode ITO (PIX) and the common transparent pixel electrode ITO (CoM). The dielectric film of liquid crystal capacitor Cpix is liquid crystal LC. Protective film PSVI
and is the midpoint potential.

The storage capacitance element C add has a midpoint potential (pixel electrode potential) Vi when the thin film transistor TPT switches.
It works to reduce the influence of gate potential change ΔVg on a. This situation can be expressed as the following formula.

ΔV lc = ((Cgs/ (Cgs+Cadd+
Cpix)) xΔ where Δvlc represents the change in midpoint potential due to ΔVg. This change ΔVlc causes a DC component applied to the liquid crystal, but the retention capacitance element C a
The larger the storage capacity of dd, the smaller its value can be. In addition, the storage capacitance element C add has the effect of lengthening the discharge time, and the thin film transistor TPT
Stores video information for a long time after it is turned off. Reducing the DC component applied to the liquid crystal LC improves the life of the liquid crystal LC,
It is possible to reduce so-called burn-in, where the previous image remains when switching LCD screens. As mentioned above, since the gate electrode GT is provided in a large size so as to completely cover the semiconductor layer AS, the overlap area with the source/drain electrodes SDI and SD2 increases, and therefore the parasitic capacitance Cgs increases and the center point The opposite effect occurs that the potential v1c becomes more susceptible to the influence of the gate (scanning) signal Vg. However, this disadvantage can also be eliminated by providing the storage capacitor element C add.

Further, in a liquid crystal display device having pixels in an intersection area of two scanning signal lines GL and two video signal lines DL, one scanning signal line GL of the two scanning signal lines GL may be
The thin film transistor TPT of the pixel selected by is divided into a plurality of parts, and the divided thin film transistors TPTI to TF
Transparent pixel electrodes ITO1 to ITO3, which are obtained by dividing the transparent pixel electrode ITO into a plurality of parts, are connected to each of T3, and each of the divided transparent pixel electrodes ITOI to ITO3 uses this pixel electrode ITO as one electrode, and the two scanning signals mentioned above are connected to each of T3. Line O
By using the other scanning signal line GL of L as a capacitor electrode line to configure the storage capacitor element C add with the other electrode, it is possible to eliminate the problem even if only a point defect occurs in a divided part of the pixel, as described above. Since the pixel as a whole is no longer a point defect, it is possible to reduce the number of point defects in the pixel, and it is also possible to reduce the direct current component applied to the liquid crystal LC by the storage capacitor element C add, which improves the life of the liquid crystal LC. can do. In particular, by dividing the pixel, it is possible to reduce point defects caused by short circuits between the gate electrode GT and source electrode SDI or drain electrode SD2 of the thin film transistor TPT, and also to connect each of the transparent pixel electrodes ITOI to ITO3 and the storage capacitor. Element C ad
It is possible to reduce point defects caused by short circuits with the other electrode (capacitor electrode line) of d. In the case of this liquid crystal display device, the number of point defects on the latter side is one third. As a result, some of the point defects in which the pixel is divided are smaller than the entire area of the pixel, making it difficult to see the point defects.

The storage capacitance of the storage capacitor element C add is 4 to 8 times (4
・CpLx (Cadd<8・Cpix), 8 to 32 times the superposition capacitance Cgs (8・Cgs<Ca
dd<32・Cgs). In addition, the scanning signal line GL is constituted by a composite film in which a first conductive film (Cr film) g1 and a second conductive film (AI2 film) g2 are superimposed, and the other electrode of the storage capacitor element C add, that is, the capacitor electrode line By configuring the branched portion with a single MPIJ made of the first conductive film g1 of the composite film, the resistance value of the scanning signal line GL can be reduced and the writing characteristics can be improved. Holding capacitor element C ad
One electrode (transparent pixel electrode ITO) of the storage capacitor element Cadd can be reliably bonded onto the insulating film GI along the step portion based on the other electrode of the storage capacitor element Cadd. wire breakage can be reduced.

In addition, the other electrode of the storage capacitor element Cadd is connected to the single-wave first electrode.
By forming the conductive film g1 and not forming the second conductive film g2 which is an AQ film, it is possible to prevent a short circuit between the other electrode and one electrode of the storage capacitor element C add due to hillocks of the AΩ film. Transparent pixel electrodes ITOI to ITO overlapped to form storage capacitor element C add
3 and the branched portion of the capacitor electrode line, similarly to the source electrode SDI, a third electrode is provided to prevent the transparent pixel electrode ITO from being disconnected when climbing over the step shape of the branched portion. An island region is provided which is composed of a first conductive film d1 and a second conductive film d2.

This island region is configured to be as small as possible so as not to reduce the area (aperture ratio) of the transparent pixel electrode ITO. In this way, the first
A second conductive film d2 having a smaller specific resistance value and smaller dimensions than the conductive film d1 and the first conductive film d1 provided thereon.
constitutes a base layer provided with the above one electrode (the third
By connecting the conductive film d3) to the first conductive film d1 exposed from the second conductive film d2 of the base layer, the storage capacitor element Cadd is reliably connected along the stepped portion based on the other electrode of the storage capacitor element Cadd. Since one electrode can be bonded, disconnection of one electrode of the storage capacitor element Cadd can be reduced. A liquid crystal display section of a liquid crystal display device in which a storage capacitor element Cadd is provided in a transparent pixel electrode ITO of a pixel is constructed as shown in FIG. 20 (equivalent circuit diagram showing the liquid crystal display section). The liquid crystal display section includes pixels, a scanning signal line GL, and a video signal line D.
It consists of repeating unit basic patterns including L. Final stage scanning signal line GL used as a capacitor electrode line
(or the first stage scanning signal, illGL) is transmitted to the common transparent pixel electrode (Vcom) I T as shown in FIG.
Connected to O. As shown in FIG. 3, the common transparent pixel electrode ITO is connected to an external wiring at the peripheral edge of the liquid crystal display device by means of a silver paste material SL. Moreover, some conductive layers (gl and g2) of this external lead wiring
is constructed in the same manufacturing process as the scanning signal IGL. As a result, the final stage scanning signal line OL (capacitive electrode line) can be easily connected to the common transparent pixel electrode ITO. In this way, by connecting the final stage of the capacitive electrode line to the common transparent pixel electrode (VCO) ITO of the pixel, the final stage of the capacitive electrode line can be configured integrally with a part of the conductive layer of the external wiring. However, since the common transparent pixel electrode ITO is connected to this external lead wire, the final stage capacitor electrode line can be connected to the common transparent pixel electrode ITO with a simple configuration. In addition, the liquid crystal display device was patented in the 1980 patent application.
Based on the DC cancellation method described in No. 25, as shown in FIG. 19 (time chart), by controlling the drive voltage of the scanning signal line DL, the DC component applied to the liquid crystal LC can be further reduced. can be reduced. In FIG. 19, Vi is an arbitrary scanning signal line GL
driving voltage. Vi+1 is the fighting voltage of the scanning signal line GL at the next stage.

Vee is a low-level driving voltage Vdmin applied to the scanning signal line GL, and Vdd is a high-level driving voltage Vdmax applied to the scanning signal line OL.

Midpoint potential v1c (18th
If the total capacitance of the pixels (Cgs+Cpix+Cadd) is C, the voltage changes Δv1 to ΔV (see figure) are as follows. ΔVt=-(Cgs/C)・V2 ΔV,=+(Cgs/C) {V1+V2)−(Cadd
/C)・V2 Δv,=-(Cgs/C)・v1 + (Cadd/C)・(V 1 + V 2) Δv
4=-(Cadd/C)・v1 Here, if the driving voltage applied to the scanning signal line OL is sufficient (see Note 1 below), the DC voltage applied to the liquid crystal LC is expressed by the following formula. .ΔV, +ΔV, = (Cadd−V 2 − Cgs
−V l )/C Therefore, Cadd−v2=Cgs
-v1, the DC voltage applied to the liquid crystal LC becomes O. [Note 1: At times t1 and t2, the change in the scanning line Vi is the midpoint potential Vl. During the period from t2 to t3, the midpoint potential Vlc is set to the same potential as the video signal potential through the signal line Xi (sufficient writing of the video signal).

The potential applied to the liquid crystal LC is almost determined by the potential immediately after the thin film transistor TPT is turned off (thin film transistor T
Is PT's off period more overwhelming than on period? ). Therefore, when calculating the direct current flowing through the liquid crystal LC, the period t■ to t can be almost ignored, and the potential immediately after the thin film transistor TPT is turned off, that is, the potential at time t3 and t. All you have to do is consider the effects during the transient period.

Note that the polarity of the video signal Vi is reversed for each frame or line, and the DC component due to the video signal itself is 0.
It is said that In other words, in the DC cancellation method, the drop caused by the drawing of the midpoint potential v1c by the superimposed capacitor Cgs is pushed up by the opening voltage applied to the storage capacitor element C add and the next stage scanning signal mGL (capacitive electrode line), and the liquid crystal L.C.
The DC component added to the can be made extremely small. As a result, the life of the liquid crystal LC of the liquid crystal display device can be improved. Of course, if the gate electrode GT is made larger to increase the light shielding effect, the storage capacitor C
What is necessary is to increase the storage capacity of add.

In this DC cancellation method, as shown in FIG. 21 (equivalent circuit diagram showing a liquid crystal display section), the first stage scanning signal line OL (or capacitive electrode line) is connected to the final stage capacitive electrode line (or scanning signal line GL). It can be adopted by connecting to.

For convenience, only four scanning signal lines iGLt are not shown in FIG. 21, but in reality, about several hundred scanning signal lines GL are arranged. The first-stage scanning signal line GL and the final-stage capacitor electrode line are connected by internal wiring within the liquid crystal display section or external lead wiring.

In this way, in the liquid crystal display device, by connecting the first-stage scanning signal line GL to the last-stage capacitive electrode line, all of the scanning signal line GL and the capacitive electrode line can be connected to the vertical scanning circuit. A DC cancellation method can be adopted. As a result, the direct current component applied to the liquid crystal LC can be reduced, so the life of the liquid crystal LC can be improved.

Although the present invention has been specifically described above based on the above embodiments, the present invention is not limited to the above embodiments, and it goes without saying that various changes can be made without departing from the gist thereof.

For example, the present invention can be applied to a liquid crystal display device in which each pixel of the liquid crystal display section is divided into two or four parts4. However, if the number of divided pixels becomes too large, the aperture ratio will decrease, so as mentioned above, , about 2 to 4 divisions is appropriate.

Furthermore, the light blocking effect can be obtained even without dividing the pixels. Further, in the above embodiment, an inverted staggered structure is shown in which gate electrode formation → gate insulating film formation → semiconductor layer formation Sakaki source/drain electrode formation, but the present invention can also be applied to a staggered structure in which the vertical relationship or the order of formation is reversed. [Effects of the Invention] As explained above, in the liquid crystal display device of the present invention, since the distance between the first and second pixel electrodes is different for each pixel, the area within each pixel is The threshold voltage at which the liquid crystal inverts varies depending on the voltage. Therefore, by controlling the magnitude of the input signal voltage, the area of the area where the liquid crystal is inverted within one pixel changes, and the aperture ratio in one pixel changes for each pixel, allowing multi-gradation and multi-color display. It can be realized.

In the present invention, the gradation can be controlled by applying a voltage in a predetermined step, instead of applying a voltage in a transient region where the liquid crystal is not sufficiently inverted, as in the past, so that the input signal voltage can be controlled. It can be easily controlled and the swing circuit of the liquid crystal display device can be simplified. In addition, in each area within one pixel, the liquid crystal is either completely inverted or not completely inverted, and the state of the liquid crystal is stable, so it is possible to achieve multi-gradation with good reproducibility. display and multicolor display can be realized.

[Brief explanation of drawings]

FIG. 1(A) is a schematic plan view of one pixel of an embodiment of the liquid crystal display device of the present invention, FIG. 1(B) is a schematic cross-sectional view of a pixel showing the first embodiment of the present invention, FIG. 1(C) is a schematic sectional view of a pixel showing a second embodiment of the present invention, FIG. 1(D)
2 is a schematic cross-sectional view of a pixel showing a third embodiment of the present invention, and FIG. 2 is a plan view of an essential part showing one pixel of a liquid crystal display section of an active matrix color liquid crystal display device to which the present invention is applied. Figure 3 is a cross-sectional view of the area taken along the section line ■-■ in Figure 2 and the area around the seal, and Figure 4 is the main part of the liquid crystal display section in which a plurality of pixels shown in Figure 2 are arranged. 5 to 7 are plan views of main parts of the pixel shown in FIG. 2 in a predetermined manufacturing process, and FIG. 8 is a plan view of the pixel shown in FIG. 4 in a state in which the color filter is superposed Main part plan, No. 9
The figure is an equivalent circuit diagram showing the liquid crystal display section of the above-mentioned active matrix type color liquid crystal display device.
-1. A sectional view of the main part of the pixel and the periphery of the seal part of the liquid crystal display part of another active matrix type color liquid crystal display device to which the present invention is applied. FIG. 12 is a plan view showing one pixel of the liquid crystal display part of the display device, FIG. 12 is a cross-sectional view of the portion taken along the line A-A in FIG. 11, and FIG. 13 is a plan view showing a plurality of pixels shown in FIG. The main part plan views of the liquid crystal display section, FIGS. 14 to 16, are as follows:
FIG. 11 is a plan view of the main part of the pixel shown in a predetermined manufacturing process, FIG. 17 is a plan view of the main part of the pixel shown in FIG. 20 and 21 are equivalent circuit diagrams showing the liquid crystal display section of the active matrix color liquid crystal display device shown in FIG. 13, respectively. It is. 1...Scanning signal line 2...Video signal line 3...One pixel 4...Gate electrode 5...Transparent glass substrate 6...First pixel electrode 7...Second pixel Electrode 8...Liquid crystal SUB...Transparent glass substrate GL...Scanning signal line DL...Video signal line TPT...Thin film transistor GT...Gate electrode SD...Source electrode or drain electrode LC...・Liquid crystal T) FT...Thin film transistor ITO...Transparent pixel electrode Figure (d) Name of the person who corrects the liquid crystal display device Name related to the case

Claims (1)

[Claims] 1. A first pixel electrode provided on a first transparent glass substrate and a second pixel electrode provided on a second transparent glass substrate, the first transparent glass substrate and the above The second transparent glass substrate is stacked at a predetermined interval so that the first pixel electrode and the second pixel electrode face each other, and the second transparent glass substrate is arranged so that the first pixel electrode and the second pixel electrode A liquid crystal is sealed between the first pixel electrode and the second pixel electrode, and one of the first pixel electrode and the second pixel electrode is divided into a plurality of parts to form a plurality of pixels, and the first pixel electrode and the second pixel electrode 1. A liquid crystal display device characterized in that the distance between two pixel electrodes is different for each pixel.